Mold segment

ABSTRACT

Roll-type briquetting machines employed for high temperature operations such as in the compaction and briquette making of heated, reduced iron ore are cooled by the use of a flexible internal cooling system employing water. The flexibility of the machine requires that mold segments be removable from the rolls. This system provides means for circulating water through the roll segments from a common source and maintaining uniform temperature on the surface of each segment on the rolls.

I United States Patent 11 1 1111 3,873,259

Kennedy Mar. 25, 1975 MOLD SEGMENT 3,184,793 5/1965 Ploarde 425/237 3,829,267 8/1974 Woodward 425/237 [75] Inventor: Frank Kennedy Pmsbulgh, 3,830,612 8/1974 Komarek 425/237 x [73] Assignee: United States Steel Corporation,

Pittsburgh, Pa, Primary E.\'aminerJr. Spicer Filed: Dec- 1973 Attorney, Agent, or F1rm-W1l11am Krayer [21] App]. No.: 422,641 [57] ABSTRACT Roll-type briquetting machines employed for high 52 us. or 425/470, 425/237, 425/363, temperature Operations Such as in the Compaction and 425/471 briquette making of heated, reduced iron ore are [51] Km. Cl. 1329c 1/00 Cooled y the use Of a flexible internal Cooling System [58] Field 01 Search 425/237, 470, 471, 363, employing Water- The flexibility of the machine 425 497; 249/1 7 R quires that mold segments be removable from the rolls. This system provides means for circulating water 5 References Cited through the roll segments from a common source and UNITED STATES PATENTS I maintaining uniform temperature on the surface of 1 each segment on the rolls. 1,358,577 11/1920 Roberts 425/470 X 2,125,814 8/1938 Rote et a1. 1. 425/470 X 1 Claim, 6 Drawing Figures PATENIEDHAR25|9I5 3.873.259

FIG. 6. F76. 5.

MOLD SEGMENT BACKGROUND OF THE INVENTION This invention relates particularly to the cooling of roll-type briquetting machines. It will be discussed particularly in connection with briquetting machines of the type disclosed in Komarek U.S. Pat. Nos. 3,077,634, 3,143,769 and 3,269,611. These patents describe a roll-type briquetting machine in which two rolls in tandem are rotated tangentially and in opposite directions. The material to be made into briquettes is forced between the rolls into the area known as the nip of the rolls. On each side of the nip is a retaining wall known as a cheek plate. As the hot, reduced ore or other material to be briquetted is forced into the nip of the rolls, and as the pressures of compaction distribute the material throughout the mold pockets, surface heat is generated on the segments which must be dissipated in order to reduce the wear and erosion of the segment parts and the means used to force the material into the nip.

The buildup of heat in the nip of the rolls also stimulates and encourages the adherence of material to the roll pockets. Adhesion of material such as heated, reduced iron ore to the mold pockets is highly undesirable because it results in deformed briquettes, breakage of segments, and reduces the efficiency of the briquetting process. Production rates of the briquetting machines are typically at the rate of 30 to 43 tons per hour. Also typically, the rolls move at from to 28 revolutions per minute; a roll may contain as many as 36 to 250 pockets around the circumference of the roll, which is about 3 feet in diameter. Accordingly, it will be seen that it is typical for a given pocket to appear in the nip of the rolls every two or four seconds.

Prior to the present invention, the heating problem was for a time considered to be extremely difficult, if not insoluble. Thereafter, a spray system was developed on the outer circumference of the roll at 180 from the nip. The use of water sprays at one point only, however, has limitations which arise mainly from the rapid increase and decrease of segment temperature with each revolution. My invention involves the use of a particular system of internal water circulation which provides cooling continuously throughout the rotation of the roll, thus maintaining a relatively constant temperature throughout.

Prior to the present invention, it has been known to use water for the internal cooling of such devices as rolls. See, for example, U.S. Pat. No. 2,650,034. Water cooling has also been used for various types of presses, molds, and dies, such as disclosed in U.S. Pat. Nos. 3,556,201, 3,525,098, 3,735,805, 3,213,491, 3,259,175 and in German Pat. No. 1,071,733. The control of temperature during an iron briquetting process is discussed in U.S. Pat. No. 3,556,772.

SUMMARY OF THE INVENTION I have invented a system for internal water cooling of briquette mold segments during operation on a tandem roll briquetting machine. The system permits the use of relatively high temperatures and compaction pressures while at the same time decreasing the incidence of sticking, and increasing the ready release of briquettes from the roll pockets.

My invention provides the circulation of water in a closed system within the roll and briquette mold segments. It is capable of removing at least 500,000 btu/- hour from a typical machine as described herein.

A preferred embodiment of my invention is shown in the drawings, of which FIG. 1 is a perspective view of an assembled roll unit including briquette mold segments, FIG. 2 is a cutaway view of the roll and its shaft, showing the mold segment seats and part of the internal water circulation system of my invention, FIG. 3 is an exploded view of a roll segment showing the seating within the segmented clamps, FIG. 4 is a detailed portion of a clamp ring, and FIGS. 5 and 6 are sectional views of the subject of FIG. 4.

Referring to FIG. 1, the assembled briquette roll unit comprises roll core 6, a pipe 24 axially within it, and peripheral roll segments 2 secured by clamps 4'having bolt and nut assemblies 18 to secure them. The roll segments 2 include briquette pockets 54.

Referring to FIG. 2, the cutaway briquette roll assembly shows the roll core 6 placed around the pipe 24. Centered on roll core 6 is the segment-supporting roll body section 3. The purpose of the roll body section 3 is to provide seats 8 in the shape of Vs. The seats 8 are designed to hold segments 2, not shown in FIG. 2.

Pipe 24 is inserted into larger trepanned hole 26 to provide equal passages through the pipe 24 and around its circumference. Collar 28 is welded to pipe 24 and ring 30 is attached to provide a watertight barrier when pipe 24 is threaded or otherwise affixed to roll core 6.

Water is introduced into pipe 24 and channeled to radial passages 34 and thence to annular groove 36 which functions as a supply manifold. The holes 38 are drilled into cover plate 40.

In FIG. 3, an exploded view of two opposed clamps and the manner of fitting on a segment is shown. The clamps 4 may be seen to be connected by bolt 18. Between them is a roll segment 2 which contains pockets 54. This assembly, as the previously described roll assembly, is conventional except for the water circulation elements described below. Operation of my invention is illustrated as follows.

Water flows through holes 38 from groove 36 to holes 42 in clamp ring 4. The holes 44 channel water into holes 46 then through holes 48 in segment 2.

Water flow is through segment 2 into outlet clamp 4, further into outlet annular groove 50 which operates as a discharge manifold, thence to radial passage 52.

It can be seen that the water exiting through the trepanned hole 26 does not intermix with the inlet water inside the pipe 24. A divided flow of cooling water is directedtin a once through passage 48 inside the segments 2 to cool the segment surfaces 54. Pipe 24 rotates with the roll; water is introduced to it from a conventional rotary joint not shown. If it is desired for the pipe to be stationary, a conventional rotary joint may be used in the interior of the roll.

A unique design feature of my invention is the manner in which the clamp rings 4, segments 2 and roll body 6 are gasketed at 56 and 58 as shown in FIGS. 4 and 6. FIG. 5 shows the obround gasket 58 inserted in retaining groove 60. FIG. 6 shows the obround gaskets 56 and 58 in operating attachment with clamp 4, tightened against roll body 6 and segment 2. The recess 62 provides a manifold-type passageway distribution header, or discharge recess, depending on the flow direction, for the cooling water to flow to or from the three holes 46 in clamp 4 to or from the five holes 48 in segment 2. The water is distributed and flows uniformly and with approximately equal velocity (i.e. plus or minus through each of the five holes, resulting in a uniform temperature over the surface of the segment pockets 54. A once-through system is preferred since no cooling tower or water treatment is required.

The arrangement of the gaskets provides for the expansion and contraction of the various components, without leakage between the joints of abutting parts. The gaskets are resilient to provide tight seals and to permit radial adjustment ofthe segments 22, to prevent rubbing of the cheek plates (not shown) or other stationary parts of the machine, and to align the segments of one roll with those of the other to obtain symmetrical briquettes.

The diameter of the holes through the segments should be sufficient to avoid the possibility of plugging by entrained solids and scale formation but large enough to remove the heat introduced to the machine during use. In the case ofa typical machine used for the manufacture of briquettes from hot reduced ore, where the temperature of the ore itself, without any heat of compaction and friction is likely to be over 900F, the holes should be large enough, that is, provide enough water, to remove 500,000 btus/hr when flowing with a velocity sufficient to achieve turbulence. As a practical matter, the holes should not be less than about onefourth inch diameter and not more than three-fourths inch diameter, although the upper limit depends mainly on the size of the machine. The achievement of turbulence is important for energy pick-up, proper mixing,

and the elimination of channeling and/or dead spots in the system. There should be at least three holes per segment, and the distance between them 'should not be less than about three-fourths of the diameter of the holes and/or greater than two times the diameter of the hole. The distance from a hole to the nearest point on the surface to be cooled should not exceed three times the distance between hole centers, and should not be less than that distance.

My invention is not limited to the above preferred and illustrative embodiments but may be otherwise practiced within the scope of the following claims.

I claim:

1. A mold segment comprising a generally V-shaped steel element having a mold surface opposite the point of the V and including at least three transverse holes for effecting the circulation of cooling water, said holes being spaced by distances at least three-fourths of their diameter and less than two times their diameter, the distance from the hole to the mold surface throughout the length of the hole being at least the distance between holes and no more than three times that dis- 

1. A mold segment comprising a generally V-shaped steel element having a mold surface opposite the point of the V and including at least three transverse holes for effecting the circulation of cooling water, said holes being spaced by distances at least three-fourths of their diameter and less than two times their diameter, the distance from the hole to the mold surface throughout the length of the hole being at least the distance between holes and no more than three times that distance. 